Prenatal exposure to older-but-lingering flame retarding chemicals called polybrominated diphenyl ethers (PBDEs) is associated with lower intelligence and hyperactivity in early childhood, according to findings presented  May 6, 2013, at the Pediatric Academic Societies (PAS) annual meeting.

PBDEs have been used for years in baby strollers, carpeting and electronics and other products. Even though nearly all PBDEs, except Deca-BDEs, were withdrawn from use in the US in 2004, the chemicals are not easily biodegradable. They are still found in older furniture, carpet pads, foams, electronics and other consumer products. The chemicals can remain in human tissue for a long time, making it possible even now for an exposed mother to transfer the chemicals to a developing fetus.

In animal studies, the chemicals have been shown to disrupt thyroid hormone and cause hyperactivity and learning problems, reports lead author Aimin Chen, MD, PhD, assistant professor in the Department of Environmental Health at University of Cincinnati College of Medicine.

The new study analyzed blood samples from 309 pregnant women enrolled in a study at Cincinnati Children's Hospital Medical Center.  Researchers also performed intelligence and behavior tests until the children in the study were 5 years old.

Maternal exposure to PBDEs was associated with deficits in child cognition at age 5 years and hyperactivity at ages 2-5 years.  A 10-fold increase in maternal PBDEs was associated with about a 4 point IQ deficit in 5-year-old children.

"Our study adds to several other human studies to highlight the need to reduce exposure to PBDEs in pregnant women," Chen says.